In 3500 BCE, the Norte Chico civilization formed its first city at Huaricanga in the Fortaleza area of north-central coastal Peru. This pre-Columbian society included approximately thirty major population centers in what is now the Norte Chico region. The civilization flourished between the fourth and second millennia BCE. Archaeological exploration near the Chillon River mouth and Ancon desert revealed settlement complexes including sites at Cerro Chivateros, Cerro Oquendo, and La Pampilla, indicating organized communities of ancient hunter-gatherers near quarries and workshop areas.